1. Field of the Invention
This concept relates generally to waterbed mattresses and more specifically to water mattresses including dry foam or fiber.
2. Discussion of the Prior Art
Water mattresses of the past have all included a water cavity or bladder formed from water impervious materials. These materials have typically included multiple sheets of polyvinylchloride which have been heat sealed together to form the bladder cavity.
In some cases sheet foam has been disposed in the water cavity to provide the water mattress with additional resiliency. This sheet of foam has been corrugated or otherwise configured to provide the upper surface of the mattress with an attractive appearance. Since the foam has tended to float on the water within the bladder, it has also been relied on to elevate the top sheet and provide a billowed appearance.
Although the foam sheets have had optimum resiliency characteristics in a dry state, such as in air, they nevertheless have improved the general resiliency of the mattress even when disposed in contact with the water in the bladder cavity.
Taking advantage of the optimum resiliency characteristics, dry foam has been disposed outside of the bladder cavity and enclosed in overlying relationship with the bladder typically in a fabric envelope. This configuration has increased the complexity of the manufacturing process since the foam and fabric envelope have had to be dealt with separately from the bladder manufacturing process. This dry foam has not been fixed to the materials forming the bladder cavity, so that it has tended to gather forming an uneven sleeping surface.